fix: formatting and address other review comments

src/background/modules/AutoRemoteFollow.js

@@ -149,7 +149,7 @@ function getInteractionType(url) {
  * @returns {void}
  */
 function onTabUpdate() {
-    browser.tabs.executeScript(null, {
+    browser.tabs.executeScript({
         file: "/content_script/mastodonInject.js"
     });
 }

src/content_script/mastodonInject.js

@@ -1,38 +1,44 @@
 "use strict";
 
 /**
- * Replacement onClick handler for Follow button
+ * Replacement onClick handler for Follow button.
  * @param {Event} event 
+ * @returns {void}
  */
 function onClickFollow(event) {
     event.stopPropagation();
     event.preventDefault();
-    const username = window.location.pathname.split(`/`).slice(-1)[0];
+    const username = window.location.pathname.split("/").slice(-1)[0];
     // activate AutoRemoteFollow
-    window.open(`/users/${username}/remote_follow`, `_blank`);
+    window.open(`/users/${username}/remote_follow`, "_blank");
 }
 
 /**
- * wait for element to appear
+ * wait for element to appear.
  * @param {string} selector
- * @param {number} timeout
+ * @param {number} timeoutDuration
  * @see {@link https://github.com/storybookjs/test-runner/blob/6d41927154e8dd1e4c9e7493122e24e2739a7a0f/src/setup-page.ts#L134}
  *  from which this was adapted
+ * @returns {Promise}
  */
-function waitForElement(selector, timeout) {
+function waitForElement(selector, timeoutDuration) {
     return new Promise((resolve, reject) => {
-        function getElement() {
-            return document.querySelector(selector);
-        }
+        const getElement = () => document.querySelector(selector);
+
+        const timeout = window.setTimeout(() => {
+            reject(new Error("waitForElement timed out"));
+        }, timeoutDuration);
 
         const element = getElement();
         if(element){
+            window.clearTimeout(timeout);
             return resolve(element);
         }
 
         const observer = new MutationObserver(() => {
             const element = getElement();
             if(element){
+                window.clearTimeout(timeout);
                 resolve(element);
                 observer.disconnect();
             }
@@ -43,24 +49,27 @@ function waitForElement(selector, timeout) {
             subtree: true
         });
 
-        window.setTimeout(() => {
-            reject();
-        }, timeout);
+        return null;
     }); 
 }
 
 /**
- * Inject replacement onClick handler for Follow button
+ * Inject replacement onClick handler for Follow button.
+ * @returns {void}
  */
 async function injectFollowButton() {
     try {
-        const followButton = await waitForElement(`.account__header__tabs__buttons button.button`, 20000);
-        followButton.addEventListener(`click`, onClickFollow);
-    } catch {
+        const followButton = await waitForElement(".account__header__tabs__buttons button:first-of-type", 20000);
+        followButton.addEventListener("click", onClickFollow);
+    } catch (error) {
         // Follow button failed to appear
     }
 }
 
+/**
+ * Initialise injection for Mastodon Follow button.
+ * @returns {void}
+ */
 async function init() {
     await injectFollowButton();
 }